Although a local area network ("LAN") communications system such as Ethernet (trademark of the Xerox Corporation) allows a plurality of transceivers to tap into the cable upon which the network relies, with rather generous limits on the maximum number of transceivers and the distance of closest approach for such transceivers, it is necessary for some purposes to determine with acceptable accuracy the location of each broadcasting transceiver on the cable. Frye, in U.S. Pat. No. 3,434,049, and Oliver et al., in U.S. Pat. No. 4,766,386, disclose the use of time domain reflectometry techniques to determine whether a given cable has a substantial impedance discontinuity, indicating the presence of a cable short, an open cable or another similar problem with transmission of signals on the LAN cable. However, these techniques do not permit the determination of source identity and location, with acceptable accuracy, of a broadcasting station on the cable that is not associated with an impedance discontinuity.
It is an object of this invention to provide apparatus that can operate within the constraints imposed by an LAN system such as Ethernet and that allows determination of location of each broadcasting transceiver on a cable in the network.